1. Field of the Invention
The invention relates to methods and devices for accelerated stability analysis, and in particular to a qualitative and quantitative direct estimation/identification of separation processes of disperse material systems (such as liquid-solid, liquid-liquid or liquid-gaseous). The invention also relates to methods and devices for the classification and quantitative characterization of slow, as well as rapid separation phenomena of disperse material systems of different volume concentration. Exemplary fields of application concern the development, selection and optimization of destabilizers, stabilizers and novel formulations for dispersions, as well as quality and process control (such as in the chemical, pharmaceutical, biotechnological, cosmetic and food industries), as well as in the process technology for separation and treatment processes.
2. Background Information
In general, a differentiation can be made between indirect and direct methods for assessing the velocity of separation phenomena of dispersions and to the prediction of stability.
Indirect methods have in common that by various analytical methods, one or more material or dispersion parameters can be determined which influence the separation behavior on the basis of known basic physical law (Stokes"" law), such as density, size distribution of the dispersed particles or the rheological behavior. However, Stokes"" law has been derived under ideal conditions (e.g. extreme dilution). Hence, for complex, concentrated material systems, separation velocity cannot be calculated a priori and stability cannot be predicted without additional reference measurements, even with extensive determination of several relevant parameters.
Direct methods (e.g., centrifuge separation, gravitation separation and so forth) determine the separation velocity via the change of local composition of the dispersion in dependence of time. For example, it is known to use normal or analytical centrifuges with highly stable dispersions (very slow separation). See German Patent No. DE 4116313.3-52 which is hereby incorporated by reference in its entirety. In this case, separation is strongly accelerated. Aside from a series of measurement-technical problems (addressed, for example, using light transmission), rapidly separating dispersions cannot be accurately examined therewith. Moreover, the resulting centrifugal forces can lead to a change in the dispersion structure. A transfer to normal storage conditions is therewith not given.
Rapidly separating dispersions allow for assessment in a gravitational field. When particles have migrated over a sufficient path due to the force of gravitation, then corresponding concentration changes can be detected. A so-called test-tube test as per DIN 51599 is known. Here, the level of the clear phase is visually read after a determined time. The results, however, are subjective and have a preciseness on the order of, for example, 0.5 mm. For minimal documentation during this proceeding, images are in some cases generated by photographic or digital cameras, and are correspondingly stored in archives. A method is also known, wherein the information of the images is subsequently quantified by image processing (e.g., the Demulsibility Tester, produced by Analis, of Belgium). However, the method accords relatively low local and temporal resolution, the results depend on the absorption properties of the disperse and fluid phase (e.g., use of white light), large original data amounts to be administered, and there is reduced ability to accelerate the separation process.
Known methods for the analysis of separations include recording the occurring concentration or structural changes at predetermined locations of the dispersion sample using suitable measurement sensors. For example, electrodes are used for determining the conductivity (e.g., apparatus available from IFAC GmbH) of conductive dispersions. See, for example, www.IFAC.de, as are optical detectors (see, for example, Japanese Patent No. 5078236, U.S. Pat. Nos. 4,099,871, 4,457,624, German Patent No. DD 216104, and German Patent No. DE-OS 3618707, the disclosures of which are all hereby incorporated by reference in their entireties). With these methods, the position of the sensors is process-technically fixed, and hence, data on the dispersion areas between these sensors is not available. This can restrict the assessment of separation processes of complex dispersions.
Scanning sensor systems (e.g. scanning sedimentometers) are also used (See for example, German Patent No. DE 3609552, Austrian Patent No. AT 397159, European Patent No. 0760092, and U.S. Pat. No. 5,783,826, which are all hereby incorporated by reference in their entireties). For example, sensors are mechanically displaced along a vertically positioned measuring cell (or vice versa), and the measurement values are collected at discrete locations in a temporarily successive fashion.
Because the measurements with scanning sensor systems are process-technically contingent, an instantaneous representation of the concentration profile or the local structure of the dispersion over the entire height of the measurement cell is not provided. Scanning times of more than 20 seconds are typical, and a repetition of the measurement is possible, at the earliest, after twice the scanning time. The analysis of the kinetics of rapid separations or of other locally dependent structural changes of dispersions therewith is not possible. With scanning sensor systems, the relative and absolute local resolution is predetermined by the mechanical construction principle (e.g., step width). Resolutions of a few micrometers come with a disproportionate increase of technical and financial expenditure.
In addition, with scanning sensor systems, microvibrations influencing the kinetics of separation phenomena are not completely excluded with mechanical principle solutions having moving sensors or measurement cells.
Moreover, the above-mentioned methods are directed to vertical, cylinder-shaped measurement cells having a circular diameter, the inexact positioning thereof being a frequent source of errors. In addition, with methods based on gravitational force, high measurement times, under certain conditions of months, have to be taken into account for dispersions of higher stability. A process-imminent quality control is thereby impractical.
The present invention is directed to methods and devices for the classification of separation phenomena.
Exemplary embodiments provide for the classification and quantitative characterization of slow, as well as rapid separation phenomena of disperse material systems of different volume concentration. The stability or instability of a dispersion can be detected, or stabilizing or destabilizing influences on a dispersion can be examined, respectively. Exemplary embodiments can provide for instantaneous, local and temporal high-resolution detection of the local composition of the dispersion over an entire height of a measurement cell, as well as the temporal change thereof in a short interval (for example, on the order of a hundredth of a second, or less), without movement of the measurement cell, transmitter or receiver. Exemplary embodiments can accommodate a differing volume concentration of the measurement sample and the corresponding target of analysis by using measurement cells having various geometrical dimensions, without further modifications of the device.
By tilting the measurement cell and the transmitter/receiver without a mutual position change, exemplary embodiments permit the separation velocity to be accelerated without the influence of additional mechanical forces, due, for example, to induction of different micro-flow pattern within the dispersion by inclination, and the analysis duration, (for example, for dispersions of higher stability), can thereby be shortened by a multiple, allowing for process-imminent quality controls.
In accordance with exemplary embodiments, methodically relevant data, as well as all original signals, as well as all manually or automatically realized evaluations, can be memorized in a data base and visualized on a monitor or output in any desired form (e.g., a hard copy produced by software). Specific program modules can be provided for the automatic methodical adaptation of the analyzer to the analyte, as well as for a direct process control through optical, acoustical or electronic signals.
Exemplary embodiments are applicable with features from known elements relating to any or all of the products to be measured, measurement cells, wave-emitting sources, and wave-receiving sensors, and can provide instantaneous shots over an entire height of the measurement cell at various azimuthal angles, despite changes of the micro-flow in the dispersion, and without additional power application. Exemplary combinations can achieve a synergetic effect in determining the stability and separation of disperse material systems.
Exemplary embodiments can focus on qualitative and quantitative direct estimation/identification of separation processes of disperse material systems (e.g., liquid-solid, liquid-liquid or liquid-gaseous) with a highest time and local resolution. Exemplary embodiments are also constituted by a variation of the micro-flow in the product to be measured, and therewith, an additional gradual acceleration of the analysis process can be performed without applying external power (e.g., centrifugation) which can be desirable with, for example, gel-stabilized dispersions.
Exemplary embodiments of the present invention are directed to a method and a device for determining the stability and separation of disperse material systems, using tubular measurement cells and wave-emitting sources and wave-receiving sensors. A software-controlled means can be provided which contains measurement cells of optional diameter for receiving a product to be measured. For the detection of local and temporal changes of the composition of the product to be measured, one or more wave-emitting sources and wave-receiving sensors can be provided, which are stationary relative to a position of the respective measurement cell. These can be arranged in such a way that the intensity distribution of the waves/radiation exiting from the sample, is detected locally and temporally over an entire height (or any desired portion) of the measurement cell. Exemplary embodiments allow for the position change of the cell and of the sources and sensors relative to the vertical force of gravitation, without changing their mutual positions.
Exemplary embodiments can include electromagnetic as well as acoustic sources and corresponding sensors, as well as means which can expand an outputted point radiation to a height (or desired portion) of the measurement cell, and align (e.g., parallel) the radiation perpendicular to the longitudinal axis of the measurement cell. The sources and sensors in particular can be configured line-shaped, or any desired shape.
Exemplary measurement cells are comprised of various materials having circular, prismatic or rectangular cross-sections, which can be varied along the longitudinal axis of the measurement cell. By means of a specific structure, several measurement cells can be analyzed independent of one another.
For an exemplary multi-channel variant, several identical measurement modules can be controlled by software, and the device can include, for the multi-channel variant, corresponding means controlled by the software, such as mirrors, plane-parallel transparent plates, an illumination unit and/or a detector unit allowing a synchronous or asynchronous analysis of the various measurement cells to be carried out.
Exemplary embodiments can include add-on contrivances, by which:
feed of an individual measurement cell support with measurement cells can ensue asynchronously (e.g., manually or by means of a robot);
the measurement cells, controlled by software, can be in situ cleaned and repeatedly filled by appropriate means similar to U.S. Pat. Nos. 4,457,624 or 4,099,871, the disclosures of which are hereby incorporated by reference in their entireties, and a sample material in each case can be analyzed;
the measurement cells can be internally thermostated (e.g., connection to a circulation) and controlled by software, cleaned and repeatedly filled, and the sample material in each case can be analyzed;
means (such as racks) can be provided for inclining a measurement module including the measurement cell, a radiation source and a sensor relative to a vertical axis; the inclining means can include manual means (e.g., crank) or, software control of, for example, a stepper motor.
Furthermore, exemplary embodiments can comprise sensors for measuring actual deviation from a vertical, the measured values of which can be polled by software and stored in a database, and fixed separate from the measurement module.
Exemplary heating and/or cooling elements, and temperature sensors for a directed temperature stabilization or for a modification of the temperature of the sample material can be included, as well as redispersion tools integrated for a homogenization before the measurement is started.
Exemplary embodiments of the entire system can also be configured as a mobile measurement device.
In accordance with exemplary embodiments, qualitative and quantitative direct estimation or identification of separation processes of disperse material systems can be achieved. Exemplary embodiments are suitable for use in, for example, the field of development, selection and optimization of destabilizers, stabilizers and novel formulations for dispersions, as well as in quality and process control. Moreover, exemplary embodiments are suitable, for example, in the process technology for separation and treatment processes and in the chemical, pharmaceutical, biotechnological, cosmetic and/or food industries.